The invention relates to sealing closures for containers in which liquid is stored under pressure and is removed under pressure. The sealing closure of the invention comprises an axially bored plug-like closing body having a conically tapered outer surface, a flange which is adapted to bear against the container top, and an annular peripheral recess disposed between the flange and the said conically tapered outer surface. Sealing means are provided in the bore and comprises two annular projections. A removable sealing cap is provided which fits into the lower opening of the bore, as well as a removable closure cap for closing the upper opening of the bore.
In a known sealing closure of the aforedescribed type, the intermediate space between the parallel ring seals (annular projections) is arranged opposite the said peripheral recess, the spacing between these ring seals corresponding essentially to the height of the peripheral recess. The sealing cap which can be fitted into the lower opening of the axial bore is essentially cylindrical, is open at one side and is provided with a radially outwardly projecting flange at the lower outer margin of the open side. This known sealing closure is used for containers, more particularly cans, which are breached with a special miniature tapping arrangement in order to tap the liquid, for example, beer, which is stored under pressure in the container. The sealing closure must on the one hand ensure that the isobarometrically stored liquid remains completely airtightly enclosed in the container, and on the other hand, on breaching, the inserted breaching spike of the tapping arrangement is sealed in such a manner as not to disturb and impair the pressure tightness.
The above-described known sealing closure operates satisfactorily under normal conditions and careful handling when driving it into the bung-hole of a container. It has, however, been observed that, for example, when the insertion of the breaching spike is not carried out absolutely axially, the seal is not always faultlessly provided by the ring seals. Moreover, the danger exists that with forceful insertion of the sealing closure in the bung-hole, the sealing cap is loosened and thereby the seal is no longer completely sound so that under certain conditions pressure gas can escape from the container.